Essential fatty acids have been recognized as important biological precursors from which all human body fats, biological membranes, and prostaglandins are synthesized. Omega-6 linoleic acid (cis .DELTA..sup.9,12) and omega-3 linolenic acid (cis .DELTA..sup.9,12,15) are two unsaturated fatty acids that have been recognized as essential. They are "essential" because mammals lack the enzymes necessary to synthesize them, and they must therefore be exogenously supplied, usually in the diet. In view of their widespread biological importance, they have in the past been used as ingredients in cosmetics, such as shampoos and conditioners. Although their beneficial effects have been recognized in the past, the widespread use of these and other fatty acids in hair and skin preparations has been limited by the instability of the fatty acids, and their propensity to undergo oxidation, degradation, and become rancid. Such reactions can impair or eliminate the desired biological effects of the fatty acids.
Hempseed oil is a natural oil that can be obtained by cold pressing hemp seeds, which are seeds from the plant species Cannabis sativa. The oil from these seeds contains a mixture of natural fats (triesters of glycerol, also known as triglycerides). In particular, the hemp seed oil is a triester of the formula ##STR2## in which about 95% of the molecular weight of the molecule is the R groups, which are fatty acids selected from the group consisting of palmitic acid, stearic acid, arachidic acid, behenic acid, palmitoleic acid, oleic acid, linoleic acid and linolenic acid. This rich mixture of fatty acids includes several especially biologically important fatty acids, such as omega-6-linoleic acid (a polyunsaturated essential fatty acid), omega-6 linolenic acid, and omega-3 linolenic acid (a polyunsaturated essential fatty acid).
The particular chemical composition of some samples of hemp seed oil has been found to have a fatty acid content of approximately the following amounts:
______________________________________ palmitic acid 5.8% saturated stearic acid 2.6% saturated arachidic acid 0.8% saturated behenic acid 0.3% saturated palmitoleic acid 0.2% monounsaturated oleic acid 11.4% monounsaturated linoleic acid 54.7% polyunsaturated, omega-6 linolenic acid 2.6% polyunsaturated, omega-6 linolenic adid 18.4% polyunsaturated, omega-3 ______________________________________
Hempseed oil has an iodine value (measure of saturation) of 166, and a very low freezing point (-20.degree. C.) because of its high essential fatty acid content. Given the high content of essential fatty acids in hemp seed oil, attempts have been made to use hemp as an herbal treatment.
Hemp seed oil products have been commercially available in recent years, but they have been less than optimal for application to hair and skin. The oils have not been substantive enough or of long term value, and they only temporarily smooth or soften the hair or skin to which they are applied. The oils can also make the hair appear greasy, produce an adverse aesthetic feel, and are easily washed out of the hair, thereby diminishing any long term effect.
U.S. Pat. No. 4,511,555 disclosed the use of an herb, such as an extract of Indian hemp leaves, for controlling dandruff. The leaves were heated in vegetable oil for 3-5 hours at a temperature of 100-190.degree. F., to produce the extract, which was blended into petroleum jelly and olive oil for application to the hair as a pomade. This patent does not mention the extraction of any hemp or hemp seed oils, but to the extent any oils would be present they would be polymerized, oxidized, or otherwise rendered less biologically active by the harsh extraction process.
Many cosmetic ingredients have been quaternized to impart a cationic charge to the ingredients, which helps improve their attraction or adherence to the skin and hair. Quaternization has primarily been applied to polymeric compositions, such as quaternary ammonium homopolymers and copolymers (U.S. Pat. No. 3,986,825), cationic polymers (U.S. Pat. No. 5,196,189), cationic resins and surfactants such as polysaccharides and polyamides (U.S. Pat. No. 5,344,643), vinylpyrrolidone/dialkylaminoalkyl acrylate or methacrylate copolymers (U.S. Pat. Nos. 4,540,507 and 4,837,012). Unfortunately, polymerization of biological substances often inactivates them, which makes these techniques unsuitable for use with biologically active materials, such as the essential fatty acids in hemp seed oil.
It is therefore a general object of the present invention to overcome the drawbacks of the prior art, in which processes for the quaternization of biologically active materials have rendered them substantially less active than the unquaternized form.
A specific object is to produce a substantive hair and skin care product which improves the natural benefits of hemp seed oil.